-
The EAPS Weekly News
November 10, 2014 Like EAPS on Facebook Follow EAPS on
Twitter
UPCOMING EAPS MEETINGS
EAPS STAFF MEETINGS Thursday, Nov. 20, 2014
9:00-10:00 a.m. HAMP 2201
~ ~ ~ ~ ~ ~ EAPS RECEPTIONS AT CONFERENCES
AGU (SAN FRANCISCO) Wednesday, Dec. 17, 2014
7:00 - 9:00 p.m. Thirsty Bear-Billar Room
AMS (PHOENIX) Tuesday, Jan. 6, 2015
6:30 - 8:30 p.m. Sheraton Phoenix Downtown Hotel
~ ~ ~ ~ ~ ~ FALL FACULTY MEETING SCHEDULE
Tuesday, Nov. 18, 2014 3:00-4:30 p.m. HAMP 3201
SPRING FACULTY MEETING SCHEDULE
Tuesday, Jan. 27th, Feb. 10th (Dean’s Visit to Dept.), Mar.
24th, and Apr. 14th, 2015
3:00-4:30 p.m. HAMP 3201
PUBLICATIONS
Qin, Zhangcai and Zhuang, Qianlai (2014) Estimating Water Use
Efficiency in Bioenergy Ecosystems Using a Process-Based Model, in
Remote Sensing of the Terrestrial Water Cycle (eds V. Lakshmi, D.
Alsdorf, M. Anderson, S. Biancamaria, M. Cosh, J. Entin, G.
Huffman,W. Kustas, P. van Oevelen, T. Painter, J. Parajka, M.
Rodell and C. Rüdiger), John Wiley & Sons, Inc, Hoboken, NJ.
doi:10.1002/9781118872086.ch30
EAPS COLLOQUIA
“Profiling Developing Tropical Storm Environments Using GPS
Airborne Radio Occultation”
Brian Murphy PhD Candidate
Tuesday, Nov. 11, 2014 at 4:00 p.m. HAMP 2201
“Opportunities and Challenges of Shale Gas Development” Mark D.
Zoback
Thursday, Nov. 13, 2014 at 4:00 p.m. Matthews Hall/Room 210
Please see attached map.
(Please see attached fall 2014 EAPS Colloquia)
EAPS NEWS
ELEMENTS MAGAZINE
The most recent issue of Elements magazine is devoted to
cosmogenic nuclides; an area in which EAPS and Purdue have become a
world leader. Two out of six articles in this feature are authored
by our own Nat Lifton and Darryl
Granger. It is an honor for our department and our faculty to be
featured so prominently in such a high profile journal read by
earth scientists who want to know about what
people in other fields are doing. We are very proud of efforts
made by both Nat and Darryl as well as PRIME lab and
Marc Caffee to make it possible. Please see attached.
http://www.facebook.com/EAPSPurduehttp://www.twitter.com/PurdueEAPS
-
~ --
EAPS OMBUDSMAN
What is an Ombudsman? The ombudsmen are an informal, neutral,
confidential resource for people in the department, especially
students, to raise questions or concerns about any aspect of their
academic experience. The EAPS ombudsman is Barbara Gibson (HAMP
2169B;
[email protected]) - please feel free to contact her if
needed.
UNDERGRADUATE AND GRADUATE STUDENT INFORMATION
OPENHATCH
On Sunday, Nov. 16th, OpenHatch and Purdue’s Computer Science
Women’s Network are hosting a day-long (12:30 - 6:30) open source
software immersion event. We invite Earth, Atmospheric, and
Planetary Science students to join us! You can sign up here:
http://purdue.openhatch.org/. You don’t need to be a programmer to
contribute to open
source, or to attend and enjoy our event. Most open source
projects are also in need of designers, translators, documenters,
bug-finders and testers. The event is open to all students. Open
source software -- software that is shared freely and
available to build upon -- has become part of our daily lives.
Popular projects like WordPress, Firefox, Adium, and Ubuntu have
millions of users. In the atmospheric sciences, agencies like the
EPA and the National Weather Service lead development of open
source projects like GEMPAK, a weather forecasting, display and
analysis software package, and CMAQ, a program for air quality
modeling, not to mention the dozens of other projects in academia
and industry. You can learn more about these projects, and start
helping out with them, at our event. Open source participation is
one way to gain real-world
skills and make connections that will last you through your
career. Volunteer staff will include professionals and academics
that use open source daily.
~ ~ ~ ~ ~ ~ BENDER VIRTUAL CAREER FAIR – EMPLOYMENT FOR
PEOPLE WITH DISABILITIES
Thursday, November 13, 2014. Students and alumni with
disabilities are invited to chat with employers. Register at
www.careereco.com/register/disability.
TALENTED WRITERS
The Writing Lab is looking for talented undergraduate writers of
all majors who demonstrate a strong interest in business,
technical, or professional writing to join us as Business &
Professional Writing Consultants. Prospective consultants will
enroll in a Spring 2015 training course which will prepare them to
work with students on a variety of workplace documents and course
assignments, including resumes, cover letters, memos, and
reports.
o Undergraduates of all majors are invited to apply for spring
2015;
o Prerequisite courses include one of ENGL 203, 306, 309, 420,
421, or 422;
o Applications must include a recommendationfrom a former
English instructor as well as acurrent résumé and cover letter.
~ ~ ~ ~ ~ ~ PETROLEUM AND GEOSYSTEMS ENGINEERING
INTERNSHIPS
Summer research internships are available for undergraduate
students within the UT Austin Petroleum and Geosystems Engineering
Department. UT PGE is currently accepting applications for interns,
where they will work for 10 weeks in the summer of 2015 for a
salary of $4000 plus on-campus housing, a meal plan and travel to
Austin. The interns will be mentored by a UT PGE faculty member and
work on a project that is of interest to them. This is a great
opportunity for an undergraduate to get research experience, learn
about the energy industry and a taste of the grad school
experience. SURI will consider application students from all
engineering and science majors with at least a 3.25 GPA. This
program only accepts students who are U.S. Citizens or permanent
residents. The deadline to apply is January 12, 2015. Apply to
PGE.
~ ~ ~ ~ ~ ~ TAIWAN SPRING BREAK TRIP
Krannert is opening spaces for the Taiwan Spring Break program,
Asian Emerging Markets and Economies, to all Purdue majors at this
time. During the program, students get to heavily interact with
students from National Chengchi University, while learning about
Asian economy and culture from the top professors and business
executives in Taipei. Students receive 1 credit for the program and
almost all costs are included in the program price. Information:
Program applications will be open until Saturday, November 15th and
we would love to have students from multiple disciplines at Purdue
participate in the program.
http://purdue.openhatch.org/https://www.careereco.com/register/disabilityhttp://www.pge.utexas.edu/http://www.krannert.purdue.edu/undergraduate/study-abroad/short-term-programs/taiwan/home.aspmailto:[email protected]
-
INTERN IN SINGAPORE SUMMER 2015
The companies include Rockwell Automation, Toshiba, Paypal,
Rolls Royce, Hershey and several others. The program is open to all
majors at Purdue and runs during the month of June. The call-out is
Wed, Nov. 12th at 6 p.m. in HAAS Rm. G-066.
~ ~ ~ ~ ~ ~ PURDUE WINTERIZATION 2014
Interested in spending a day helping your community and having
fun with your friends? Winterization is a community service project
in which students from Purdue University assist in preparing the
yards and homes of the elderly and disabled in Tippecanoe County
for winter. This event will take place Saturday, November 15, 2014.
Breakfast and lunch are provided for volunteers. For more
information and to register please visit here.
~ ~ ~ ~ ~ ~ LBC CERTIFICATE
Interested in a certificate for Learning Beyond the Classroom?
Visit LBC to find out more.
~ ~ ~ ~ ~ ~ NASA EARTH AND SPACE SCIENCE FELLOWSHIP
(NESSF) PROGRAM
NASA announces a call for graduate fellowship proposals to the
NASA Earth and Space Science Fellowship (NESSF) program for the
2015-2016 academic years. This call for fellowship proposals
solicits applications from accredited U.S. universities on behalf
of individuals pursuing Master of Science (M.Sc.) or Doctoral
(Ph.D.) degrees in Earth and space sciences, or related
disciplines. The purpose of NESSF is to ensure continued training
of a highly qualified workforce in disciplines needed to achieve
NASA’s scientific goals. Awards resulting from the competitive
selection will be made in the form of training grants to the
respective universities. The deadline for NEW applications is
February 2, 2015,
and the deadline for RENEWAL applications is March 16, 2015. The
NESSF call for proposals and submission instructions
are located at the NESSF 15 solicitation index page at
http://nspires.nasaprs.com/ - click on "Solicitations" then click
on "Open Solicitations" then select the "NESSF 15" announcement.
Also refer to “Proposal Submission Instructions” and “Frequently
Asked Questions” listed under “Other Documents” on the NESSF 15
solicitation index page. All proposals must be submitted in
electronic format only
through the NASA NSPIRES system. The advisor has an active role
in the submission of the fellowship proposal. To use the NSPIRES
system, the advisor, the student, and the university must all
register. Extended instructions on how to submit an electronic
proposal package are posted on the NESSF 15 solicitation index page
listed above. You can register in NSPIRES at
http://nspires.nasaprs.com/.
For further information contact Claire Macaulay, Program
Administrator for NESSF Earth Science Research, Telephone: (202)
358-0151, E-mail: [email protected] or Dolores Holland,
Program Administrator for NESSF Heliophysics Research, Planetary
Science Research, and Astrophysics Research, Telephone: (202)
358-0734, E-mail: [email protected].
~ ~ ~ ~ ~ ~ DINING ETIQUETTE WITH MR. ANTHONY CAWDRON
Purdue students are invited to a Professional Dining Etiquette
Event with Mr. Anthony Cawdron in the Union's
west faculty lounge November 10th from 6-7p.m. The event is
presented by Purdue CCO, Alpha Kappa Psi and Beta Alpha Psi and
sponsored by ArcelorMittal. Mr. Anthony Cawdron is a dining
etiquette expert and coordinator of Westwood (President Daniel’s
residence). Students can reserve a seat for the presentation any
time before the
event (11/10) using this link. View the Facebook event page here
.
OTHER NEWS
CLIMATE CHANGE DIRECT HIRE AUTHORITY INTERNSHIP OPPORTUNITIES IN
THE NATIONAL PARK
SERVICE PARTNERS
National parks and NPS programs develop and oversee structured
projects in one or more of the following interdisciplinary areas:
climate change science and monitoring; resource conservation and
adaptation; policy development; sustainable park operations;
facilities adaptation; and communication/interpretation/education.
During the internship, students apply critical thinking and problem
solving skills to climate change challenges and communicate with
diverse stakeholders. Interns who successfully complete the YLCC,
an approved Direct Hire Authority Internship program, will be
eligible to be hired non-competitively into subsequent federal jobs
once they complete their degree program. These jobs would be in the
Department of Interior (DOI), NPS, or one of the other bureaus
within the DOI. An intern must qualify for the job in order to be
hired non-competitively.
Quick Facts and Deadlines: • The YLCC is managed cooperatively
with the University of Washington • Internship opportunities and
application forms are posted on parksclimateinterns.org •
Internships are 11-12 weeks (40 hours/week) during the summer •
Interns are paid $14/hour plus benefits • Applications are accepted
from early December 2014 until late January 2015
This is a great opportunity for students who might be interested
in a climate change internship. Upon completion, students will be
eligible to be hired non-competitively into subsequent federal
positions once they have completed
http://www.purduewinterization.org/http://science.purdue.edu/Current_Students/learning-beyond-the-classroom/enroll.htmlhttps://urldefense.proofpoint.com/v2/url?u=http-3A__nspires.nasaprs.com_&d=AAMFAg&c=jF7FvYH6t0RX1HrEjVCgHQ&r=p_kmtdKbcxzYOYWhwJpYmQ&m=7gc_mSHXX3ASgm2wSsktbSJmWTGeyM_DPGk61Q1odPo&s=72e9nk9xl3F2bLn_IKmGsqSnskOqqALEls7_VJM2WeA&ehttps://urldefense.proofpoint.com/v2/url?u=http-3A__nspires.nasaprs.com_&d=AAMFAg&c=jF7FvYH6t0RX1HrEjVCgHQ&r=p_kmtdKbcxzYOYWhwJpYmQ&m=7gc_mSHXX3ASgm2wSsktbSJmWTGeyM_DPGk61Q1odPo&s=72e9nk9xl3F2bLn_IKmGsqSnskOqqALEls7_VJM2WeA&emailto:[email protected]:[email protected]://goo.gl/zbZICbhttps://www.facebook.com/events/1560809187483840/?notif_t=plan_editedhttp:parksclimateinterns.org
-
their degree programs. Application deadline is January 30, 2015.
For More Information contact Tim Watkins, Climate
Change Response Program, NPS, [email protected]
~ ~ ~ ~ ~ ~ INDIANA STATE DEPARTMENT OF HEALTH
October 29, 2014
The first cases of Ebola Virus Disease (EVD) diagnosed in the
United States have heightened awareness of our global community and
this serious disease. It also raised the level of concern for the
safety of travelers both to the affected counh·ies, and those
returning to Indiana from an affected country, and the safety of
the academic community. The Ebola virus is not spread through the
air, by water or
food, or by casual contact. People with Ebola can only spread
the Ebola virus when they have symptoms. There is no lmown risk of
transmission if someone does not have symptoms. Ebola is only
spread through direct contact with blood or body fluids (including
but not limited to urine, saliva, feces, vomit and semen, or a
needlestick) of a person who is sick with Ebola or the body of a
person who has died from Ebola. Currently in the U.S., individuals
at risk for developing
EVD are those who have arrived in the U.S. from Guinea, Liberia,
or Sierra Leone within the past 21 days (the maximum incubation
period for Ebola virus). Previous travel to these countries outside
the 21-day incubation period is not a risk factor for Ebola.
Individuals who have had direct contact with identified
Ebola cases in the U.S. may also be at risk for the EVD if that
contact occurred at the time the case was symptomatic. Ebola
symptoms include fever, headache, nausea, vomiting, diaIThea,
muscle or body aches, and fatigue. The Indiana State Department of
Health (ISDH) website has more information about EVD at
www.statehealth .in.gov. The Centers for Disease Control and
Prevention (CDC)
has prepared a document specifically addressing the unique
concerns of colleges, universities, and students around the EVD
occurring in the West African countries of Guinea, Liberia, and
Sierra Leone. You can find that information at: http://wwwnc.cdc
.gov/travel/page/advice-for-college s-universities-and-student
s-about-ebola-in -west-africa. To read more, please see
attached.
APPLICATIONS SOUGHT FOR NEXT IMPACT COHORT November 3, 2014
The IMPACT program is now taking applications for the spring
2015 cohort, and applications are due by 5 p.m., Nov. 28th. The
application link and information about the program are available at
www.purdue.edu/impact.
IMPACT (Instruction Matters: Purdue Academic Course
Transformation) is a campus-wide initiative begun in 2011 by the
Provost's Office for the redesign of classes. Its aim is to engage
students more fully in their learning, thereby improving
competency, retention and completion in classes that serve students
across the entire campus. It is related to Purdue Moves and the
University's efforts to be the national forerunner in
transformative higher education.
For more information on the program, contact Chantal
Levesque-Bristol, director of the Center for Instructional
Excellence, at [email protected]
BIRTHDAYS
Nov. 10th
Nov. 11th Tim Filley Frank Bakhit
Nov. 12th Gerald Krockover Nov. 12th Ken Ridgway
mailto:[email protected]://wwwnc.cdc/http://www.purdue.edu/impacthttp://www.purdue.edu/purduemoves/mailto:[email protected]
-
What- people t-h1nk a6ou-t during ~our c..onterenc..e
t-aH-.o(,
1-k':j! -n...t•
-
Profiling Developing Tropical Storm Environments Using GPS
Airborne Radio Occultation
An extensive set of airborne radio occultation (ARO) data has
been collected by GISMOS, the GNSS Instrument System for
Multi-static and Occultation Sensing, while deployed during the
PRE-Depression Investigation of Cloud systems in the Tropics
(PREDICT) experiment in 2010 to study developing tropical storms in
the southern Atlantic and Caribbean region. This is the first time
RO observations have been used to investigate the spatial and
vertical variability of moisture with sufficient density (~ 7
profiles within 450 km of the storm center ) to characterize the
mesoscale storm environment. GISMOS applies the radio occultation
technique to remotely sense the atmosphere by measuring the phase
delay and amplitude of received GPS radio signals due to the
density and water vapor content of the atmosphere. High resolution
vertical profiles of atmospheric refractivity below the aircraft
altitude are obtained from the ARO data. Both geodetic GPS
receivers using conventional phase-lock loop tracking and a high
rate 10 MHz GPS recording system were used to collect GPS signal
data over twenty-six missions. The ARO profiles retrieved from the
geodetic receivers consistently agree within ~2 % of refractivity
profiles calculated from the European Center for Medium-range
Weather Forecasting (ECMWF) model interim re-analyses as well as
from nearby dropsondes and radiosondes. The number of profiles and
the minimum altitude sampled by the profiles obtained from the
geodetic receivers were limited by the conventional phase-lock loop
tracking which does not perform optimally in the lower tropical
atmosphere where moisture levels result in sharp changes in
refractivity causing rapid changes in GPS signal phase. A much
larger set of profiles extending farther below aircraft height is
obtained from the 10 MHz recorded GPS signal data using an open
loop tracking algorithm, which is implemented in a software
receiver. We will demonstrate the consistency of the combined
dropsonde and RO dataset with increasing moisture in the
mid-to-upper tropopause over the hurricane genesis time period for
Karl.
-
Purdue University Joint Earth, Atmospheric, and Planetary
Sciences /
Physics and Astronomy Colloquia S. Thomas Crough Memorial
Lecture
Mark D. Zoback Prof. of Geophysics, Stanford University
Opportunities and Challenges of Shale Gas Development Thursday,
November 13 4:00 PM – 5:00 PM Mathews Hall Room 210 Refreshments at
3:30 in Mathews 210
Open to the public
Abstract: The proven ability to produce large quantities of
natural gas from organic-rich shale formations is changing the
energy picture in many parts of the world. In this talk I will
discuss steps that can be taken to assure such resources are
developed in an optimally efficient and environmentally responsible
manner. Responsible development of shale gas resources has the
potential to substantially reduce greenhouse gas emissions in the
near term and significantly reduce air pollution and benefit public
health. I will discuss several on-going research projects
investigating the wide variety of factors affecting the successful
gas production from these extremely low permeability formations and
procedures for managing the risks of earthquakes triggered by
injection of hydraulic fracturing waste water.
Dr. Mark D. Zoback is the Benjamin M. Page Professor of
Geophysics at Stanford University. Dr. Zoback conducts research on
in situ stress, fault mechanics, and reservoir geomechanics with an
emphasis on shale gas, tight gas and tight oil production. Dr.
Zoback was one of the principal investigators of the SAFOD project
in which a scientific research well was successfully drilled
through the San Andreas Fault. He is the author of a textbook
entitled Reservoir Geomechanics published in 2007 by Cambridge
University Press, the author/co-author of 300 technical papers and
holder of five patents. Dr. Zoback has received numerous awards and
honors, including the 2006 Emil Wiechert Medal of the German
Geophysical Society and the 2008 Walter H. Bucher Medal of the
American Geophysical Union. In 2011, he was elected to the U.S.
National Academy of Engineering and in 2012 elected to Honorary
Membership in the Society of Exploration Geophysicists. He recently
served on the National Academy of Engineering committee
investigating the Deepwater Horizon accident and the Secretary of
Energy’s committee on shale gas development and environmental
protection.
-
[Type text]
PURDUE UNIVERSITY Department of Earth, Atmospheric, and
Planetary Sciences
Colloquia – Fall 2014Thursdays at 3:30 PM, Room 1252 HAMP
(unless noted)
Sept. 4 When Engineering Geology Meets Geotechnical
Engineering
Sept. 9
Gary Luce, Knight Piesold & Co., AEG President
The Impact of Climate Change and Agricultural Activities on
Water
Host: West
Cycling in Northern Eurasia Yaling Liu, PhD Candidate Advisor:
Zhuang
Tuesday, 4:00PM, Room 2201/HAMP
Sept. 11 The DOE Accelerated Climate Modeling for Energy Project
Dr. Robert Jacob, Argonne National Laboratory Host:
Harshvardhan
Sept. 18 The Origins of Volatile-rich Solids and Organics in the
Outer Solar Nebula Prof. Fred Ciesla, University of Chicago Host:
Minton
Sept. 25 Long-term Morphological Changes in Mature Supercell
Thunderstorms Following Merger with Nascent Supercells
Prof. Ryan Hastings, Purdue University Sept. 30 Making Weather
and Climate Data More Usable for Agriculture Across
the U.S. Corn Belt Olivia Kellner, PhD Candidate Advisor:
Niyogi
Tuesday, 4:00PM, Room 2201/HAMP
Oct. 2 New Perspectives on Tidewater Glacier Mass Change Dr. Tim
Bartholomaus, University of Texas-Austin Host: Elliott
Oct. 9 Sulfur Cycling on Mars from a Perspective of Sulfur-Rich
Terrestrial Analogs Prof. Anna Szynkiewicz, University of Tennessee
Host: Horgan
Oct. 16 Climate Impacts and Extremes in Large Earth System Model
Ensembles Prof. Ryan Sriver, University of
Illinois-Champaign/Urbana Host: Wu
Oct. 21 Towards a Paradigm Shift in the Modeling of Soil Carbon
Decomposition for Earth System Models
Yujie He, PhD Candidate Advisor: Zhuang Tuesday, 4:00PM, Room
2201/HAMP
Oct. 23 Anthropogenic Signals in InSAR Prof. Rowena Lohman,
Cornell University Host: Elliott/Flesch
Oct. 28 Giant Impacts on the Asteroid Vesta Tim Bowling, PhD
Candidate Advisor: Melosh
Tuesday, 4:00PM, Room 2201/HAMP
Oct. 30 Abiotic and Biogeochemical Controls on Reactive Nitrogen
Cycling on Boundary Layer Surfaces
Prof. Jonathan Raff, Indiana University Host: Shepson
(continued on next page)
-
PURDUE UNIVERSITY Department of Earth, Atmospheric, and
Planetary Sciences
Colloquia – Fall 2014 (cont.)
Nov. 6 Andean Foreland Basins: A Thermochronologic Perspective
on Sediment Provenance, Deformation, and Basin Thermal
Histories
Prof. Julie Fosdick, Indiana University Host: Ridgway
Nov. 11 Profiling Developing Tropical Storm Environments Using
GPS Airborne Radio Occultation
Brian Murphy, PhD Candidate Advisor: Sun/Haase Tuesday, 4:00PM,
Room 2201/HAMP
Nov. 13 Shale Gas Development and the Environment Prof. Mark
Zoback, Stanford University Host: Nowack
Thursday, 4:00pm, Room 210/MTHW (joint with the Physics
Dept.)
Nov. 20 The Role of Monsoon Circulation on Tropopause
Variability Prof. Yutian Wu, Purdue University
Dec. 4 CSI Patagonia: Tracking Glacial and Climate Dynamics over
the Last Glacial Cycle Alessa Geiger, University of Glasgow Host:
Harbor
[Type text]
-
The Nuts and Bolts of Cosmogenic Nuclide Production
Tibor J. Dunai1 and Nathaniel A. Lifton2
Supernova explosions, such as the one that
formed the Crab Nebula, are the major source
of cosmic rays. CREDIT: NASA/ESA / J. HESTER
1811-5209/14/0010-347$2.50 DOI: 10.2113/gselements.10.5.347
(ARIZONA STATE UNIVERSITY), STSCI-2005-37
O ver the last 60 years, our understanding of how cosmic rays
produce cosmogenic nuclides has grown from basic physical
considerations. We introduce the different types of cosmic ray
particles and how their COSMIC RAY PARTICLES flux varies with
altitude, latitude, and time. Accurately describing these
varia-
tions remains a challenge for some regions when calculating
production rates. At t he top of t he E a r t h’s atmosphere,
galactic cosmic rays We describe current and emerging computational
methods for calculating are dominated by protons (87%)
production rates that address this challenge. Continuing
developments in and α-particles (12%), with a small our
understanding of modern and prehistoric cosmic ray fluxes and
energy contribution of heavier nuclei
(~1%). Upon entering the Earth’s spectra in Earth’s atmosphere
and at its surface are bound to contribute in atmosphere, these
primary cosmic
the future to more robust applications. rays interact with the
atoms in the air to produce secondary cosmic KEYWORDS: cosmogenic
nuclide production, reaction, scaling factor, cosmic ray rays. Some
of these secondary particles (neutrons and muons) are responsible
for most of the atmospheric and in situ cosmo-genic nuclides on
Earth. INTRODUCTION
Cosmic rays are high-energy charged particles that impinge on
the Earth from all directions from space. The majority of cosmic
ray particles are atomic nuclei, but they also include electrons,
positrons, and other subatomic particles. Typical energy levels
range from a few mega–electron volts (MeV) up to ~1020 eV, with a
maximum energy of a few hundred MeV per nucleon (Eidelman et al.
2004).
For the purposes of in situ and atmospheric cosmogenic nuclides,
the term cosmic rays usually refers to galactic cosmic rays, which
originate from sources outside the Solar System. Supernova
explosions, which occur approximately once every 50 years in our
galaxy, produce most galactic cosmic rays, with energies of up to
1015 eV (Eidelman et al. 2004; Diehl et al. 2006). The galactic
cosmic ray flux is generally assumed to be isotropic and to have
been approxi-mately constant over the last 10 million years (Leya
et al. 2000). Good entry-level reviews on cosmic ray physics can be
found, for example, in Rossi (1964) and in reviews on geologic
applications of cosmogenic nuclides (Gosse and Phillips 2001; Dunai
2010). In the following section, we draw from these sources, and
their references, to introduce the nature of cosmic ray particles
and the mechanisms of cosmogenic nuclide production.
Nucleons The high energies of the primary (and many secondary)
cosmic rays are well in excess of the binding energies of atomic
nuclei (typically 7–9 MeV per nucleon). Consequently, the dominant
nuclear reaction is that of spallation, the process by which
nucleons are sputtered off target nuclei. Spallation-produced
nucleons largely continue in the direction of the impacting
particle and can retain enough energy to keep on inducing
spallation in other target nuclides, producing a nuclear cascade in
the Earth’s atmosphere (FIG. 1).
Because neutrons do not lose energy through ionization as do
protons, the composition of cosmic rays undergoes changes from
proton-dominated to neutron-dominated over the course of the
nuclear cascade. At sea level, neutrons constitute 98% of the
nucleonic cosmic ray flux. However, energy losses incurred with
each interaction result in the mean energy of the secondary neutron
flux being signifi-cantly lower than that of the primary flux (FIG.
1).
Muons In addition to producing secondary atmospheric neutrons,
collisions of high-energy primary cosmic rays with atomic nuclei
high in the atmosphere produce elemental particles known as pions,
which decay within a few meters of travel to either positively or
negatively charged muons. Muons can be considered the heavier
brother of the electron (206.7 times heavier).
Muons interact only weakly with matter—therefore, they have a
much greater penetration depth than nucleons, and hence are the
most abundant cosmic ray particles at sea level. However, due to
stronger interaction with matter, the
1 Institute for Geology and Mineralogy, University of Cologne
Zülpicher Str. 49b, 50674 Köln, Germany E-mail:
[email protected]
2 Departments of Earth, Atmospheric, and Planetary Sciences, and
Physics and Astronomy, Purdue University 550 Stadium Mall Drive,
West Lafayette, IN 47907-2051, USA E-mail: [email protected]
ELEMENT S, VOL . 10, PP. 347–350 347 OCT OBE R 2014
mailto:[email protected]:[email protected]:1811-5209/14/0010-347$2.50
-
I I I I I I I I
I
I
I
a. I
I
I
I
I
I
I
I
I n µ I
I l I I I I I I I I I I I
a. I
__ .. __ I
I
I
I
I
I I
t I I I I
( )'( )'
-
nucleonic component dominates atmospheric and terres-trial
cosmogenic nuclide production. Muons, in turn, are responsible for
the majority of subsurface production.
COSMOGENIC NUCLIDES Cosmogenic nuclides are the products of
interactions of primary and secondary cosmic ray particles with
atomic nuclei. At the Earth’s surface, more than 98% of the
cosmo-genic nuclide production arises from secondary cosmic ray
particles, such as neutrons and muons. Depending on the energy of
these particles, a range of nuclear reactions can produce
cosmogenic nuclides (FIG. 1).
Spallation In spallation reactions, high-energy nucleons
(largely neutrons at ground level) collide with atomic nuclei
(“target nuclei”) and knock off protons and neutrons, leaving
behind a lighter residual nucleus. The mass differ-ence between a
target nucleus and the lighter product is usually a few atomic mass
units. Thus, target elements with nuclide masses nearest to the
resulting cosmogenic nuclide usually contribute most to its
production.
Neutron Capture The majority of neutrons in the nuclear cascade
eventually slow down to energies corresponding to the temperature
of their surroundings. These “thermal” neutrons (energies of ca
0.025 eV) can subsequently be captured by nuclei. Some thermal
neutron–capture reactions have very high probabilities of
occurrence and can produce appreciable amounts of cosmogenic
nuclides (e.g. 3He, 36Cl).
THE ATMOSPHERIC NUCLEAR CASCADE
softening of energy spectrum
increasing atmospheric depth / atm. pressure
+
N
P, N: high-energy (>10 MeV) secondary protons and neutrons
carrying the nuclear cascade
n, p, : secondary particles not carrying the nuclear cascade
± , ±, e±: pions, muons, electrons, and positrons
primarycosmic ray particle
target nucleus (e.g. N, O, Ar)
P N
n p P p
N n p n P
e -
e N p p
e± n p
n N n
residual nuclei are “cosmogenic nuclei” N n
n p
electromagnetic mesonic nucleonic
Nuclear reactions in the atmosphere produce atmospheric
cosmogenic nuclides as well as secondary
FIGURE 1
particles, mostly neutrons. The latter are responsible for the
cosmo-genic nuclides measured in minerals. FIGURE REDRAWN AFTER
DUNAI (2010)
Muon Reactions There are two main types of muon reactions
leading to cosmogenic nuclide production: negative muon capture and
high-energy (fast) muon interactions. Negative muons that have been
decelerated by ionization to thermal energies (termed “stopped
muons”) can be captured by an atom’s electron cloud, and they
quickly cascade to the lowest electron shell. There they decay, or
are captured by the nucleus where they neutralize one proton. The
probabilities for negative muon–capture reactions are much lower
than those involving neutrons.
Fast muons give rise to Bremstrahlung (“braking radia-tion”),
which produces gamma ray photons. This phenom-enon occurs when
charged particles slow down due to interactions with other charged
particles. Such muon-derived gamma rays can be of sufficiently high
energy to produce secondary neutrons from nuclei, the so-called
photoneutrons, which may produce cosmogenic nuclides. They
generally have a very low abundance and become important only at
depths greater than 20 m below the Earth’s surface, where fast
muons remain as the sole reaction-inducing “survivors” of the
cosmogenic cascade.
PRODUCTION RATES AND SCALING FACTORS The production rates of
cosmogenic nuclides are a function of the energy spectrum of the
impacting cosmic ray particles and the corresponding reaction
probabilities for target nuclei (Reedy 2013). The energy spectrum
itself is a function of altitude and position in the geomagnetic
field. As discussed in von Blanckenburg and Willenbring (2014 this
issue), nuclide production occurs both in atmospheric gases
(“atmospheric”) and in the minerals of the upper several meters of
the Earth’s surface (“in situ”). In the atmosphere, nuclide
production rates are typically estimated from theoretical and/or
numerical models (e.g. Masarik and Beer 1999), while nuclide
delivery is computed from atmospheric circulation models (Heikkilä
et al. 2013). In contrast, terrestrial production rates of in situ
cosmo-genic nuclides are typically experimentally established at
sites that have independently determined ages (e.g. moraines, lava
flows) and well-constrained exposure histo-ries (i.e. no
significant prior exposure, erosion, burial, or other disturbance
that can impact the cosmogenic nuclide inventory in the rock since
initial exposure) (Gosse and Phillips 2001; Dunai 2010).
Identifying suitable calibration sites for terrestrial
produc-tion rates requires careful characterization, and the number
and geographic distribution of these sites remain limited. Scaling
factors are required to translate the local production rates
obtained at calibration sites to values valid elsewhere on the
globe, where practitioners may use cosmogenic nuclides to obtain
exposure ages and rates of geological processes. Again, this is
because the cosmic ray energy spectrum varies spatially. Scaling
factors must also account for temporal variations in geomagnetic
and atmospheric shielding at a given location that can affect the
cosmic ray flux and its energy spectrum (FIG. 2).
Geomagnetic and Atmospheric Shielding Primary cosmic rays are
charged particles and are thus affected by Earth’s magnetic field.
At a given location, particles with kinetic energy below a certain
threshold cannot penetrate the Earth’s magnetic field and approach
the Earth’s surface. This threshold is referred to as the “cutoff
rigidity,” or RC, and is defined as the momentum of a particle per
unit charge (in gigavolts, GV).
ELEMENT S 348 OCT OBE R 2014
-
• ....~ ["loo .... ' ~
~, .... '~ .... I"'- """' ...... I'-,, ~ ~ ~ ....
... I'-,, ~ .... .:::' '"" ~ .... -- ....... - ..... .... , ....
, .... , .... , .... , .... , .... , .... , .... , ... , .... ....
, .... , .... ....
• • I
I • . • I .. I -· .. ... ... I .. ..
r-./ ... - ... ~ ..... - - ----I I I .,
-
-
A
B
Scaling Factor
A 1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
Sea Level
LSD Lal (1991)/Stone (2000) Desilets and Zreda (2003)
Secondary neutrons produced in the atmospheric nuclear cascade
attain a maximum flux at an altitude of about 16 km (Lal and Peters
1967). Below that level, their abundance decreases approximately
exponentially with atmospheric depth, which is described by the
attenuation length (FIG. 2B). As a rule of thumb, the nucleonic
cosmic ray flux decreases by half for every 1000 m decrease in
altitude (Dunai 2010).
Systematic changes in the secondary cosmic ray spectrum as a
function of atmospheric depth and RC lead to corre-sponding
variations in attenuation lengths (Lifton et al. 2014). Current
scaling models account for this variation by directly varying
attenuation lengths (Dunai 2001;
0 2 4 6 8 10 12 14 16 18 20 Desilets and Zreda 2003) or by
parameterizing altitudinal [90] [52] [43] [36] [30] [24] [17] [6]
and latitudinal variation in other ways (Lal 1991; Lifton
et al. 2014). RC (GV) [Geomagnetic Latitude (°N)] It is worth
noting that while meteoric cosmogenic nuclides,
such as 10Be, are also produced in the atmosphere largely by
spallation reactions, applications of such meteoric 10Be
B 140 are instead concerned with fluxes of the nuclide from
the
Scaling Factor
10
8
6
4
2
0 1,050 950 850 750
Atmospheric Depth (g cm-2) 0 GV 15 GV
total inventory in the atmospheric column above a given site
(Willenbring and von Blanckenburg 2010). It is signifi-cant that
>99% of the atmospheric inventory is produced above 3 km
altitude—thus, no altitude scaling is required for most of Earth’s
surface. Rather, the 10Be production signal is dominated by the
high cosmic ray fluxes in low RC regions (Willenbring and von
Blanckenburg 2010).
Once produced, meteoric 10Be quickly adsorbs to aerosol
particles that are transported by atmospheric circulation and
120
Scaling Factor
100
80
60
40
20
0 1,050 950 850 750 650 550 450 350
[700] [1620] [2620] [3750] [5000] [6500] [8250]
Atmospheric Depth (g cm-2) [Altitude (m)]
delivered to the Earth’s surface by either dry or wet
deposi-tion. Combination of 10Be production and atmospheric general
circulation models indicates that 10Be fluxes are dominated by wet
deposition—therefore, mid-latitudes that experience high
precipitation also experience the highest fluxes (Willenbring and
von Blanckenburg 2010; Heikkilä et al. 2013). Comparison of (A)
latitude scaling factors at sea level
and (B) altitude scaling for two cutoff rigidities (RC). FIGURE
2
(A) Scaling model of Lifton et al. (2014) as a representation of
the atmospheric nucleon flux (abbreviated as LSD). Earlier scaling
models based on nuclear disintegrations and various neutron
detec-tors (Lal 1991, reparameterized by Stone 2000; and Desilets
and Zreda 2003) are presented for comparison. The large discrepancy
200.90
0.70
RC
SFinstantaneous
SF10 integrated
SF14 integrated
12
at sea level between Lal (1991) and LSD is due to different
geomag-0.85 18netic parameterization in the former. (B) Altitudinal
scaling for the
LSD model at low and high RC values. The differences between the
two curves arise from two effects: sea level variation in the
nucleon flux as a function of RC, and variation in the attenuation
length of the nucleon flux as a function of both RC and atmospheric
depth (Lifton et al. 2014). Inset shows scaling in the lower 2600 m
of the atmosphere.
Modern RC values are approximately zero near the poles, where
essentially all energies present in the primary flux can penetrate
the magnetic field. This value increases to
0.80 16
Scaling Factor
0.75 14
RC (GV)
0.65 10 0.60 8 0.55 6 0.50 4
approximately 17 GV near the equator (ca 50 % of the 0.45 2polar
flux at sea level) (FIG. 2A). At RC < 1–2 GV (≥ ca 60°
geomagnetic latitude), the lowest-energy particles do not 0.40 0
have enough energy to generate an atmospheric cascade, 0 25 50 75
100 125 150 and so toward the poles the increases in the number of
Age (ka) particles that enter the atmosphere do not yield
corre-
FIGURE 3 The time variations in atmospheric nucleon flux (LSD)
scaling factors for sea level and an equatorial location
sponding increases in the flux responsible for cosmogenic
nuclide production.
are predicted using the geomagnetic field record employed in The
cosmic ray spectrum at high latitudes is not sensitive to temporal
changes in the geomagnetic field. Hence, terres-trial production
rates are usually normalized to hypothet-ical values at sea level
and high latitudes. However, the effects of secular geomagnetic
field variations on nuclide production become more pronounced with
increasing RC (at lower latitudes) and need to be considered when
calcu-lating nuclide production in the past (Dunai 2001; Desilets
and Zreda 2003; Lifton et al. 2008; FIG. 3).
Lifton et al. (2014). Note the inverse covariation of the
instanta-neous variations of the relative cosmic ray flux and the
cutoff rigidity (RC) at the high RC location. The integrated cosmic
ray flux (i.e. the time-averaged scaling factor applicable to a
given age), as relevant for exposure dating utilizing in situ
cosmogenic nuclides, is shown for 10Be and 14C. Due to the
integrated nature, the high-amplitude variations are dampened with
increasing exposure time. For long exposure, integrated production
rates of 10Be and 14C differ according to their half-lives. No
variations would be observed in either time-varying RC or flux
intensity at low RC locations, e.g. at >60° geomagnetic
latitude. SF = scaling factor; ka = thousand years.
ELEMENT S 349 OCT OBE R 2014
-
Scaling Factors for In Situ neutron energy spectra and the lack
of accurate neutron reaction probability functions; both have
become recently Cosmogenic Nuclide Production available (Sato et
al. 2008 and references therein; Reedy
Computationally complex calculations are required to 2013).
These new studies (Argento et al. 2013; Lifton et consider the
effects of spatial and temporal variations in al. 2014) indicate
that nuclide-specific scaling factors may the geomagnetic field and
atmospheric pressure on scaling be warranted for some nuclides,
such as 3He. They also of in situ nuclide production. To allow
nonspecialists to indicate that the larger contribution of protons
at high perform these analyses, user-friendly calculators are now
elevations, which are undercounted by neutron monitors available
(e.g. Balco et al. 2008). The scaling factors that (Clem and Dorman
2000), needs to be considered for are currently used perform well
for generally describing nuclide production. the relative flux of
cosmic rays as a function of altitude, latitude (Stone 2000; Dunai
2001; Desilets and Zreda 2003; CONCLUSIONS Balco et al. 2008;
Lifton et al. 2008), variations in geomag-netic field strength
(Dunai 2001; Desilets and Zreda 2003; This brief review presents
the fundamental principles of Lifton et al. 2008), and changes in
solar activity (Lifton cosmogenic nuclide production in the
atmosphere and in et al. 2008). At latitudes greater than 30º and
elevations terrestrial settings. The foundations for this science
were below 3 km, their results are generally very similar (Balco
initially laid over 50 years ago, but recent advances in our et al.
2008). However, large differences between models abilities to model
temporal variations in nuclide produc-(up to 30%) emerge for
estimates at lower latitudes and tion are certain to propel the
field forward. In the coming higher elevations. These variations
arise from the different years, these developments will help to
ensure that the neutron flux proxies used (neutron monitors,
photographic rapid progress in accurately measuring cosmogenic
nuclides emulsions) and their responses to changes in the neutron
(Christl et al. 2014 this issue) will be matched by our
under-energy spectrum (Lifton et al. 2014). standing of the rates
at which these nuclides are produced.
Recent advances have made it feasible to consider the
ACKNOWLEDGMENTS temporal changes in the energy spectrum
quantitatively and estimate their influence on nuclide production
The authors thank Pieter Vermeesch, Greg Balco, and an (Argento et
al. 2013; Lifton et al. 2014). Previously, this anonymous reviewer
for their constructive and helpful omission was due to the lack of
detailed environmental comments on the manuscript.
REFERENCES Argento DC, Reedy RC, Stone JO (2013)
Modeling the earth’s cosmic radiation. Nuclear Instruments &
Methods in Physics Research Section B 294: 464-469
Balco G, Stone JO, Lifton NA, Dunai TJ (2008) A complete and
easily acces-sible means of calculating surface exposure ages or
erosion rates from 10Be and 26Al measurements. Quaternary
Geochronology 3: 174-195
Christl M, Wieler R, Finkel RC (2014) Measuring one atom in a
million billion with mass spectrometry. Elements 10: 330-332
Clem JM, Dorman LI (2000) Neutron monitor response functions.
Space Science Reviews 93: 335-359
Desilets D, Zreda M (2003) Spatial and temporal distribution of
secondary cosmic-ray nucleon intensities and applications to in
situ cosmogenic dating. Earth and Planetary Science Letters 206:
21-42
Diehl R and 15 coauthors (2006) Radioactive 26Al from massive
stars in the Galaxy. Nature 439: 45-47
Dunai TJ (2001) Influence of secular variation of the
geomagnetic field on production rates of in situ produced
cosmogenic nuclides. Earth and Planetary Science Letters 193:
197-212
Dunai TJ (2010) Cosmogenic Nuclides: Principles, Concepts and
Applications in the Earth Surface Sciences. Cambridge University
Press, Cambridge, 198 pp
Eidelman S and 33 coauthors (2004) Review of particle physics.
Physics Letters B592: 1-1109
Gosse JC, Phillips FM (2001) Terrestrial in situ cosmogenic
nuclides: theory and application. Quaternary Science Reviews 20:
1475-1560
Heikkilä U, Beer J, Abreu JA, Steinhilber F (2013) On the
atmospheric transport and deposition of the cosmogenic
radio-nuclides (10Be): A review. Space Science Reviews 176:
321-332
Lal D (1991) Cosmic ray labeling of erosion surfaces: in situ
nuclide produc-tion rates and erosion models. Earth and Planetary
Science Letters 104: 424-439
Lal D, Peters B (1967) Cosmic ray produced radioactivity on
earth. In: Flugg S (ed) Handbook of Physics, vol 46/2. Springer,
Berlin, pp 551-612
Leya I, Lange H-J, Neumann S, Wieler R, Michel R (2000) The
production of cosmogenic nuclides in stony meteor-oids by galactic
cosmic-ray particles. Meteoritics & Planetary Science 35:
259-286
Lifton NA, Smart DF, Shea MA (2008) Scaling time-integrated in
situ cosmo-genic nuclide production rates using a continuous
geomagnetic model. Earth and Planetary Science Letters 268:
190-201
Lifton N, Sato T, Dunai TJ (2014) Scaling in situ cosmogenic
nuclide production rates using analytical approximations
to atmospheric cosmic-ray fluxes. Earth and Planetary Science
Letters 386: 149-160
Masarik J, Beer J (1999) Simulation of particle fluxes and
cosmogenic nuclide production in the Earth’s atmosphere. Journal of
Geophysical Research D 104: 12099-12111
Reedy RC (2013) Cosmogenic-nuclide production rates: Reaction
cross section update. Nuclear Instruments & Methods in Physics
Research Section B 294: 470-474
Rossi B (1964) Cosmic Rays. McGraw-Hill, New York, 268 pp
Sato T, Yasuda H, Niita K, Endo A, Sihver L (2008) Development
of PARMA: PHITS-based analytical radiation model in the atmosphere.
Radiation Research 170: 244-259
Stone JO (2000) Air pressure and cosmo-genic isotope production.
Journal of Geophysical Research 105(B10): 23753-23759
von Blanckenburg F, Willenbring JK (2014) Cosmogenic nuclides:
Dates and rates of Earth-surface change. Elements 10: 341-346
Willenbring JK, von Blanckenburg F (2010) Meteoric cosmogenic
Beryllium-10 adsorbed to river sediment and soil: Applications for
Earth-surface dynamics. Earth-Science Reviews 98: 105-122
ELEMENT S 350 OCT OBE R 2014
-
Cosmogenic Nuclides and Erosion at the Watershed Scale
Darryl E. Granger1 and Mirjam Schaller2
1811-5209/14/0010-369$2.50 DOI: 10.2113/gselements.10.5.369
Landscapes are sculpted by a variety of processes that weather
and erode bedrock, converting it into soils and sediments that are
moved downslope. Quantifying erosion rates provides important
insights into a wide range of questions in disciplines from
tectonics and landscape evolu-tion to the impacts of land use.
Cosmogenic nuclides contained in quartz sediment provide a robust
tool for determining spatially averaged erosion rates across scales
ranging from single hillslopes to continental river basins and are
providing fundamental clues to how landscapes evolve. Cosmogenic
nuclides in buried sediments contain unique information about
paleo–erosion rates up to millions of years in the past. This
article explores some of the basic ideas behind various methods
used to infer catchment-wide erosion rates and highlights recent
examples related to problems in tectonics, climate, and land
use.
KEYWORDS: cosmogenic nuclide, erosion, paleoerosion, river
sediment
INTRODUCTION At the grandest scale, Earth’s topography
represents an accumulation of potential energy from mantle
convection and tectonics, balanced by decay from chemical
weath-ering and physical erosion. Over timescales of 103–106
years, hillslope erosion, soil formation, and sediment
accumulation define the distribution and fertility of soil upon
which our societies depend. There is a critical need to understand
how soil erosion from land use is depleting this natural resource
and how modern rates compare with those from the past. Climate
change also affects erosional processes in complicated ways, which
can be difficult to discern without accurate measurements of
erosion rates over various timescales.
Curiously, the problem is that the rate of erosion is a tricky
thing to measure. It is a measure of something that isn’t there
anymore, and of how quickly it went away. What is needed is a
sensitive way to measure how much material was once at a given
place and the rate at which that material was lost to dissolution,
erosion, and sediment transport. There have been a number of
traditional approaches to the problem. For example, over long
timescales (millions of years), one can use thermochronology to
infer the rate of rock cooling due to exhumation by erosion from
kilometers below the surface (Reiners and Shuster 2009).
1 Department of Earth, Atmospheric, and Planetary Sciences
Purdue University, West Lafayette, IN 47907-2051, USA E-mail:
[email protected]
2 Department of Geosciences, University of Tübingen 72074
Tübingen, Germany E-mail: [email protected]
Cosmogenic nuclides in sand from an active river
bed (here in the Pamir Mountains) disclose the modern erosion
rate of
an entire watershed. Sediment from river
terraces (like those seen beneath the village)
provides the “paleo– erosion rate”: the
erosion rate prevailing at the time of sediment
deposition. PHOTO COURTESY OF ELENA GRIN
Over very short timescales of years to decades, sediment and
solute fluxes from a watershed can be monitored, but these
measure-ments are difficult to make with accuracy and may not
capture important but infrequent events. A better approach over
timescales from decades to millennia is to measure sediment acc
umula-tion in lakes and reservoirs or in datable sedimentary
deposits, such as alluvial fans. Unfortunately, these measurements
requ ire special circumstances and can be
subject to considerable uncertainty due to spatial variations in
sedimentation rate and in sediment-trapping efficiency. There is an
important middle ground over timescales of 103–105 years in which
rocks weather and soils form, climate changes from glacial to
interglacial, rivers incise or aggrade, and civilizations rise and
fall. This is the timescale that belongs to cosmogenic nuclides.
Over the past two decades, cosmogenic nuclides have emerged as the
method of choice for inferring erosion rates over spatial scales
that can be as small as a single outcrop to as large as watersheds
spanning a continent.
DETERMINING EROSION RATES
Theory and Methods Cosmogenic nuclides such as 10Be (half-life,
t1/2, = 1.39 My) and 26Al (t1/2 = 0.702 My) are produced in
minerals such as quartz by reactions with secondary cosmic ray
neutrons, protons, and muons (for details see Dunai and Lifton 2014
this issue). These nuclides can be used to infer erosion rates
because their production rates within a mineral grain depend on
their proximity to the Earth’s surface. Production rates decrease
exponentially with depth in rock or soil (with a mean cosmic ray
penetration length of ~60 cm in rock of density 2.6 g cm-3). For an
eroding surface, this means that the cosmogenic nuclide
concentration integrates the history of a grain’s approach toward
the surface. In other words, the cosmogenic nuclide concentration
contained in a mineral grain today reflects how quickly the
overlying mass went away.
Mathematically, it can be shown that the cosmogenic nuclide
concentration in an eroding rock is inversely proportional to
erosion rate (Lal 1991). Erosion, as used
ELEMENT S, VOL . 10, PP. 369–373 369 OCT OBE R 2014
mailto:[email protected]:[email protected]:1811-5209/14/0010-369$2.50
-
IGURE
-
• •
here, refers to the combination of physical erosion and chemical
weathering that removes mass near the surface. Early in the
development of cosmogenic nuclide applica-tions, it was recognized
that bedrock outcrops can be used to determine the denudation
history of that particular rock. However, in the mid-1990s
researchers realized that cosmo-genic nuclides in detrital sediment
grains can also be used to determine erosion rates [for reviews see
Bierman and Nichols (2004) and Granger and Riebe (2013)].
Two key realizations led to interpreting cosmogenic nuclides in
sediment. The first was that for a well-mixed soil eroding at
steady state (and in the absence of a high degree of chemical
weathering within the soil), the average concentration of
cosmogenic nuclides in the soil is the same at all soil depths.
This concentration is equal to the concentration contained in the
surface of a rock outcrop eroding at the same rate. In other words,
for a given erosion rate, a sample of well-mixed soil has exactly
the same concentration as exposed bedrock. The effects of chemical
weathering are somewhat more complex, as they vary with depth, and
an entire research field has emerged dedicated to interpreting
weathering rates with cosmogenic nuclides (e.g. Dixon and Riebe
2014 this issue).
The second key to interpreting cosmogenic nuclides in sediment
is that for well-mixed stream sediment, the average concentration
in the sediment yields the average erosion rate in the watershed
(FIG. 1). This relies on the assumptions that sediment is supplied
at a rate that is proportional to the erosion rate, that the
mineral being analyzed (i.e. quartz) is evenly distributed
throughout the entire catchment, and that the cosmogenic nuclide in
question was absent before the rock approached the surface.
It is worth examining these assumptions in detail. We begin with
the idea that detrital sediment from well-mixed soil on a hillslope
has a cosmogenic nuclide concentration that is inversely
proportional to the hillslope erosion rate. For a watershed that is
eroding homogeneously (i.e. every-where at the same rate), then the
concentration in stream sediment is equal to that of the soils on
the hillslopes and the stream sediment yields the erosion rate. In
most cases we can ignore sediment storage and transport time in the
stream system, which occurs much faster than the timescale of
erosion rates, that is, the time to erode the landscape by 60 cm.
For a watershed that is eroding heterogeneously, a surprisingly
simple solution emerges if we consider the flux-averaged cosmogenic
nuclide concentration. That is, areas of the landscape that are
eroding quickly provide a large fraction of the quartz but have a
low cosmogenic nuclide concentration; conversely, areas eroding
slowly provide less quartz but have a high cosmogenic nuclide
concentration. In this case, the average cosmogenic nuclide
concentration in the sediment reflects the spatially averaged
erosion rate from the entire watershed. Remarkably, the equation to
determine the erosion rate from an entire watershed is functionally
identical to the equation used to determine the erosion rate from a
single eroding outcrop. For example, the cosmogenic nuclides
contained in a single sample of sand can yield the spatially
averaged erosion rate of a water-shed ranging in size from the
catchment of a small upland creek to the entire Amazon River basin
(FIG. 2; Wittmann et al. 2011).
While the assumption of well-mixed and representative stream
sediment may hold approximately true, landslides or other such
episodic events may deliver an overwhelming load of sediment that
temporarily biases the average. If the preponderance of a sample
comes from just one landslide, then the inferred erosion rate will
reflect primarily only that area. Moreover, if the landslide
incorporates fresh
Cosmic rays Cosmic rays
Cosmogenic nuclide production
Landslide (non-steady erosion)
If production = export Sediment storage in for steady erosion,
no decay
N = P L/ ε terraces
N: Nuclide concentration P : Average production rate L: Cosmic
ray penetration depth (R/l ≈ 60 cm) ¡:
Catchment-averagederosionrate
Cosmogenic nuclide export from the landscape
FIGURE 1 An eroding landscape provides sediment that can be
analyzed to determine its erosion rate. Because cosmo-genic nuclide
concentrations are inversely proportional to erosion rates, the
flux-weighted 10Be concentration reflects the spatially averaged
erosion rate. Care must be taken to avoid the influence of
landslides, which can temporarily bias the sediment budget, and to
avoid catchments with extensive sediment storage. Sediment in
archives such as terraces can be used to determine paleo–erosion
rates at the time of sediment deposition. Penetration length Λ =
160 g cm-2; density ρ = 2.6 g cm-3 .
F 2 Sampling river sand for cosmogenic nuclide determi-nation in
the Qilian Shan, northern China. A single
sample of 10–100 g of quartz can yield the spatially averaged
erosion rate of the sediment-contributing area upstream. PHOTO
COURTESY OF KAI HU
bedrock or saprolite, then the cosmogenic nuclide concen-tration
will be lowered and the inferred erosion rate will be faster than
the long-term average. On the other hand, if landsliding dominates
sediment delivery in the water-shed, then it is important to sample
that material or the inferred erosion rate will be too slow. The
best solution is to sample a sufficiently large catchment with
enough landslides so that any single event does not significantly
influence the average cosmogenic nuclide concentration (e.g.
Yanites et al. 2009).
Timescale of Erosion The timescale over which in situ–produced
cosmogenic nuclides measure erosion rates is one of the major
strengths of the method, but this also limits the sorts of
problems
ELEMENT S 370 OCT OBE R 2014
-
-
Appa
rent
ero
sion
rate
(m/M
y)
200
100
Actual erosion rate
0 0 5 10 15 20
Time (ky)
FIGURE 3 The apparent erosion rate inferred from
cosmogenicnuclides can take thousands of years to respond to an
actual change in surface erosion rates. The response time, or the
time it takes for the apparent erosion rate to match the real
erosion rate, depends on both the erosion rate and the soil
thickness. The graph shows the apparent erosion rate in response to
a step change in erosion rate from 100 to 200 m/My, for soil
thicknesses of 0, 100, and 200 cm, calculated for typical rock
density of 2.6 g cm-3 and soil density of 1.5 g cm-3. For thin
soils the apparent erosion rate has increased by 90% of the actual
change within ~9 ky, while for 200 cm thick soils the same increase
in apparent erosion rates takes over 15 ky.
to which cosmogenic nuclides can be applied. Because cosmogenic
nuclides integrate the history of production rates and because
production rates fall off exponentially with depth, for a steady
erosion rate the concentration is equivalent to the mineral
residence time within the top 160 g cm-2 (~60 cm in rock of density
2.6 g cm-3, or ~1 m in soil of density 1.6 g cm-3). In other words,
the timescale of bedrock erosion is equal to the time it takes to
lower the landscape by ~60 cm, roughly equivalent to the timescale
of soil formation in many landscapes. This timescale implies that
cosmogenic nuclides effectively dampen rapid changes in erosion
rate. If erosion rates change suddenly— for example, due to recent
land use or climate change— then the cosmogenic nuclide
concentration in the soil will change only slowly, with a response
time determined by both the soil mixing depth and the time taken to
erode ~60 cm of rock (FIG. 3). The damped response time means that
the cosmogenic nuclide concentration measured in soils today
represents the long-term average erosion rate, which is usually
independent of recent changes in land use and soil degradation.
Examples of Catchment-Wide Erosion Rates Over the past 20 years,
erosion rates have been estimated by measuring the cosmogenic
nuclides contained in thousands of river-sediment samples from
virtually every climatic and tectonic environment in the world
(e.g. Portenga and Bierman 2011; Covault et al. 2013 and references
therein). Generally, these erosion rates are based on the
measure-ment of 10Be produced in situ in quartz. Several persistent
themes have emerged from the data.
One surprising conclusion from these cosmogenic nuclide– based
erosion rates is that climate is less important for regulating
erosion rates than previously assumed. While erosion rates
certainly vary strongly under conditions of climatic extremes where
erosional processes are fundamen-tally different (for example,
erosion is slow in hyperarid deserts with little biological
activity and fast in glacial and periglacial environments), climate
generally plays a secondary role in determining erosion rates over
most of the planet. Climate strongly affects the degree of soil
weathering (Dixon and Riebe 2014), but the total erosion rate is
more commonly determined by factors such as river and hillslope
gradients that are adjusted to balance local uplift. Thus, erosion
rates on low-relief continental shields are generally slow
regardless of climate (~1–10 m/My), while they are much faster
(~103–104 m/My) on rapidly uplifting mountain ranges.
The conclusion that landscape erosion rates are ultimately set
by tectonics driving river incision and hillslope erosion rather
than by climate has a number of implications. Perhaps the most
important is that cosmogenic nuclide– based erosion rates can be
used as a proxy for local river incision and uplift rates (e.g.
Wobus et al. 2005). This is a powerful notion for landscapes at
dynamic equilibrium because it suggests that a handful of sand can
provide the local incision and uplift rates (Kirby and Whipple
2012).
The numerous cosmogenic nuclide measurements now available allow
comparison of erosion rates over different timescales.
Catchment-averaged erosion rates from cosmo-genic nuclides can be
compared to short-term suspended-and dissolved-sediment loads in
rivers (e.g. Wittmann et al. 2011; Covault et al. 2013).
Interestingly, Covault et al. (2013) found that the vast majority
of cosmogenic nuclide–based erosion rates are faster than those
inferred from monitored sediment yield. This tendency was first
noticed by Kirchner et al. (2001), who invoked the impor-tance of
large but infrequent events in sediment delivery. While the
abundances of cosmogenic nuclides average such variability,
stream-gauging methods are likely to miss the largest and most
important events that may happen only once in a decade or a
century. In addition, sediment storage in floodplains tends to
buffer rapid changes in sediment supply due to land use (Wittmann
et al. 2011). Only in the most highly modified landscapes or in
landscapes with very low sediment storage capacity do modern
erosion rates consistently exceed cosmogenic nuclide–based erosion
rates (e.g. Hewawasam et al. 2003).
PALEO–EROSION RATES If modern-day river sediment contains
information about the erosion rate of its source area, then
sedimentary deposits should be able to tell us about paleo–erosion
rates and how erosion rates have varied through time in response to
changes in climate or tectonics.
Estimates of paleo–erosion rates provide powerful insights into
the behavior of ancient landscapes. It must be recog-nized,
however, that the cosmogenic nuclides that are generally useful for
determining erosion rates, such as 10Be and 26Al in quartz, are
radioactive. Also, cosmogenic nuclide production does not fully
stop even after several meters of burial. Thus, accurate
paleo–erosion rate determi-nations require correcting for loss due
to radioactive decay as well as continued production by deeply
penetrating muons. The slower the paleo–erosion rate and the more
deeply buried the sediment, the further back in time one can infer
paleo–erosion rates—generally up to 5–10 million years.
Of course, accurate paleo–erosion rate determinations require
knowing the depositional age of the sediment. But what if the age
is not known independently? The beauty of cosmogenic nuclides is
that it is possible to date the sediment directly using “burial
dating.” Measuring at least two nuclides in the same mineral grains
(such as 10Be, 26Al, and/or 21Ne in quartz; Balco and Shuster 2009)
allows one to solve for the burial age and the paleo–erosion rate
simultaneously.
ELEMENT S 371 OCT OBE R 2014
-
-
• • • • ,.e
[ - I
tt.~.. . .. . . I 1~~-.... I t= --1 ~:. -~ I
Examples of Paleo–erosion Rates A good example of how
paleo–erosion rates can be estimated over glacial/interglacial
timescales comes from the pioneering work of Schaller et al.
(2002). In their study of sediments in terraces of European rivers,
they found that erosion rates were roughly twice as fast during the
Last Glacial Maximum (LGM) as they are today. Estimates show that
the ~80 m/My determined for the LGM became much slower, to ~30–40
m/My, through the Holocene to the present. The faster rates may be
due to frost-cracking and/or periglacial processes that accelerated
erosion and soil transport during the LGM (e.g. Delunel et al.
2010).
Paleo–erosion rates can also be determined from buried sediment
over much longer timescales of millions of years to decipher how
landscapes have responded to climate change and tectonic uplift
(Schaller et al. 2004). Paleo– erosion rates (and burial dates)
allow one to explore how erosion rates and valley-incision rates
have varied at the same site over millions of years, and thus to
quantify how landscapes have responded to long-term climate change
and uplift. For example, a compilation of paleo–erosion rate
determinations that span million-year timescales (FIG. 4) records
the varied responses of landscapes to the expan-sion of Northern
Hemisphere glaciation near 2.5 My ago. Together these types of
studies provide an opportunity to examine the influence of
long-term climate change on hillslope erosion rates.
Measurements of cosmogenic nuclides also show that erosion rates
have increased in many glaciated or partially glaciated watersheds,
even during interglacials. This is true in the northern Swiss Alps
(Haeuselmann et al. 2007), the Sierra Nevada of California, USA
(Stock et al. 2004), and the Tian Shan in China (Charreau et al.
2011) (FIG. 4). Erosion rates have increased in some unglaciated
watersheds as well, particularly in areas subject to a periglacial
climate. Schaller et al. (2004) found increased erosion in the
Meuse River, the Netherlands, likely due to both climate change and
uplift of the Ardennes Mountains. A dramatic increase in erosion
rate is documented in an unglaciated valley in the Sangre de Cristo
Range, Colorado, USA (Refsnider 2010). Anthony and Granger (2007)
studied sediment in caves along the Cumberland Plateau in the
unglaci-ated southeastern United States and showed that paleo–
erosion rates systematically increase in the Pleistocene hundreds
of kilometers south of the Laurentide ice sheet margin.
Interestingly, data from Mammoth Cave in central Kentucky (Granger
et al. 2001) do not show any change in paleo–erosion rates across
this same climatic transition, even though the site is closer to
the ice margin.
DEVELOPING TRENDS: METEORIC 10BE While the discussion thus far
has focused on 10Be produced in situ within mineral grains, there
is another, much larger, inventory of meteoric 10Be in soil. 10Be
is produced in the atmosphere and delivered to the surface by wet
and dry deposition (e.g. Dunai and Lifton 2014). As a fallout
radio-
nuclide, meteoric 10Be is incorporated into a variety of
archives, including snow and ice; lacustrine, estuarine, and marine
sediment; manganese nodules on the sea floor; and soil.
Measurements of meteoric 10Be have been used to address a wide
range of geologic problems, from snow and ice accumulation to
sediment recycling in subduc-tion zones. We focus here on the
specific use of meteoric 10Be for determining erosion rates. For
recent reviews, see Willenbring and von Blanckenburg (2010), Graly
et al. (2010), and Granger et al. (2013).
Meteoric 10Be is a particle-reactive species that adsorbs
strongly to mineral grains, particularly clays, for soil pH greater
than about 6. Unlike in situ–produced 10Be, the meteoric variety
migrates within the soil profile, to a depth determined largely by
soil pH, soil texture, and grain size. More recently, the 10Be/9Be
ratio of beryllium adsorbed to sediment has been used to
simultaneously determine the erosion rate and the degree of
chemical weathering of bedrock within a watershed. The 10Be is
derived from meteoric fallout while the 9Be comes from the chemical
weathering of bedrock (von Blanckenburg et al. 2012). Advantages of
the meteoric technique are that only ~1 gram of fine-grained
material is required and that the 10Be/9Be ratio is nearly
independent of lithology.
Tian Shan, China
Sangre de Cristo Mtns., USA
Sierra Nevada, USA
Meuse River, the Netherlands
Pale
o-er
osio
n Ra
te (m
/My)
600 Siebenhengste, Swiss Alps
400
200
0 3000
2000
1000
0 60
40
20
0 60
40
20
0 10
8 6 4 2
0 600
400
200
0 80
60
40
20
0
Cumberland Plateau, USA
Mammoth Cave, USA
0 1 2 3 4 5 6 7 8 9
Age (My)
FIGURE 4 Paleo–erosion rates from ancient sediment as a function
of time for seven northern-latitude sites that
span at least 1 million years. All but one show increasing
erosion rates and/or erosional variability, whether for slowly
eroding landscapes such as the Cumberland Plateau, USA, or the
Meuse River in the Netherlands where maximum erosion rates are 60
m/ My or for high mountains such as the Swiss Alps or the Tian
Shan, China, eroding more than 10 times faster. All ages and
erosion rates are plotted as originally reported by the authors
(cited in the text) and have not been adjusted to a uniform 10Be
production rate and half-life, which would result in minor
changes.
ELEMENT S 372 OCT OBE R 2014
-
During the early years of cosmogenic nuclide applica-tions,
meteoric 10Be was widely used for exploring surface processes
because of its relatively high atmospheric concen-trations. This
approach, however, was largely eclipsed by measurements of the in
situ–produced variety in the early 1990s as methods were developed
for determining 10Be contained in quartz. Recent years have seen a
resurgence in the meteoric variety’s popularity, but one must
recog-nize that beryllium mobility in the environment can be
complex and is still poorly understood. Meteoric 10Be holds great
promise for exploring erosion rates and sediment transport, as well
as changing environmental conditions.
SUMMARY Cosmogenic nuclides are now the “gold standard” for
deter-mining erosion rates of rocks and watersheds. The method is
rooted in the physics of energetic-particle attenuation,
which allows geologists to query a rock about the material that
used to be on top of it and the rate at which the material was
lost. A handful of sand from a riverbed can tell us about the
average erosion rate upstream. Sedimentary archives offer a unique
record of how erosion rates have changed through time. Cosmogenic
nuclides are finally allowing geologists to answer age-old
questions about how the landscapes and soils around us reflect
their combined legacy of climate, tectonics, and land use.
ACKOWLEDGMENTS We would like to acknowledge the helpful comments
by the guest editors as well as reviews by P. Belmont, B.
Bookhagen, and V. Godard.
REFERENCES Anthony DM, Granger DE (2007) A new
chronology for the age of Appalachian erosional surfaces
determined by cosmogenic nuclides in cave sediments. Earth Surface
Processes and Landforms 32: 874-887
Balco G, Shuster DL (2009) 26Al–10Be–21Ne burial dating. Earth
and Planetary Science Letters 286: 570-575
Bierman PR, Nichols KK (2004) Rock to sediment—slope to sea with
10Be—rates of landscape change. Annual Review of Earth and
Planetary Sciences 32: 215-255
Charreau J and 11 coauthors (2011) Paleo-erosion rates in
Central Asia since 9 Ma: A transient increase at the onset of
Quaternary glaciations? Earth and Planetary Science Letters 304:
85-92
Covault JA, Craddock WH, Romans BW, Fildani A, Gosai M (2013)
Spatial and temporal variations in landscape evolu-tion: Historic
and longer-term sediment flux through global catchments. Journal of
Geology 121: 35-56
Delunel R, van der Beek PA, Carcaillet J, Bourlès DL, Valla PG
(2010) Frost-cracking control on catchment denudation rates:
Insights from in situ produced 10Be concentrations in stream
sediments (Ecrins–Pelvoux massif, French Western Alps). Earth and
Planetary Science Letters 293: 72-83
Dixon JL, Riebe CS (2014) Tracing and pacing soil across slopes.
Elements 10: 363-368
Dunai TJ, Lifton NA (2014) The nuts and bolts of cosmogenic
nuclide production. Elements 10: 347-350
Graly JA, Bierman PR, Reusser LJ, Pavich MJ (2010) Meteoric 10Be
in soil profiles – A global meta-analysis. Geochimica and
Cosmochimica Acta 74: 6814-6829
Granger DE, Riebe CS (2013) Cosmogenic nuclides in weathering
and erosion. In: Drever JI (ed) Surface and Groundwater, Weathering
and
Soils. Treatise on Geochemistry 5, Elsevier, 36 pp, doi:10.1016/
B978-0-08-095975-7.00514-3
Granger DE, Fabel D, Palmer AN (2001) Pliocene–Pleistocene
incision of the Green River, Kentucky, determined from radioactive
decay of cosmogenic 26Al and 10Be in Mammoth Cave sediments. GSA
Bulletin 113: 825-836
Granger DE, Lifton NA, Willenbring JK (2013) A cosmic trip: 25
years of cosmo-genic nuclides in geology. GSA Bulletin 125:
1379-1402
Haeuselmann P, Granger DE, Jeannin P-Y, Lauritzen S-E (2007)
Abrupt glacial valley incision at 0.8 Ma dated from cave deposits
in Switzerland. Geology 35: 143-146
Hewawasam T, von Blanckenburg F, Schaller M, Kubik P (2003)
Increase of human over natural erosion rates in tropical highlands
constrained by cosmogenic nuclides. Geology 31: 597-600
Kirby E, Whipple KX (2012) Expression of active tectonics in
erosional landscapes. Journal of Structural Geology 44: 54-78
Kirchner JW and 6 coauthors (2001) Mountain erosion over 10 yr,
10 k.y., and 10 m.y. time scales. Geology 29: 591-594
Lal D (1991) Cosmic ray labeling of erosion surfaces: in situ
nuclide produc-tion rates and erosion models. Earth and Planetary
Science Letters 104: 424-439
Portenga EW, Bierman PR (2011) Understanding Earth’s eroding
surface with 10Be. GSA Today 21(8): 4-10
Refsnider KA (2010) Dramatic increase in late Cenozoic alpine
erosion rates recorded by cave sediment in the southern Rocky
Mountains. Earth and Planetary Science Letters 297: 505-511
Reiners PW, Shuster DL (2009) Thermochronology and landscape
evolution. Physics Today 62: 31-36
Schaller M, von Blanckenburg F, Veldkamp A, Tebbens LA, Hovius
N, Kubik PW (2002) A 30 000 yr record of erosion rates from
cosmogenic 10Be in Middle European river terraces. Earth and
Planetary Science Letters 204: 307-320
Schaller M, von Blanckenburg F, Hovius N, Veldkamp A, van den
Berg MW, Kubik PW (2004) Paleoerosion rates from cosmogenic 10Be in
a 1.3 Ma terrace sequence: Response of the River Meuse to changes
in climate and rock uplift. Journal of Geology 117: 127-144
Stock GM, Anderson RS, Finkel RC (2004) Pace of landscape
evolution in the Sierra Nevada, California, revealed by cosmogenic
dating of cave sediments. Geology 32: 193-196
von Blanckenburg F, Bouchez J, Wittmann H (2012) Earth surface
erosion and weathering from the10Be (meteoric)/9Be ratio. Earth and
Planetary Science Letters 351-352: 295-305
Willenbring JK, von Blanckenburg F (2010) Meteoric cosmogenic
Beryllium-10 adsorbed to river sediment and soil: Applications for
Earth-surface dynamics. Earth-Science Reviews 98: 105-122
Wittmann H, von Blanckenburg F, Maurice L, Guyot J-L, Filizola
N, Kubik PW (2011) Sediment production and delivery in the Amazon
River basin quantified by in situ-produced cosmo-genic nuclides and
recent river loads. GSA Bulletin 123: 934-950
Wobus C, Heimsath A, Whipple K, Hodges K (2005) Active
out-of-sequence thrust faulting in the central Nepalese Himalaya.
Nature 434: 1008-1011
Yanites BJ, Tucker GE, Anderson RS (2009) Numerical and
analytical models of cosmogenic radionuclide dynamics in
landslide-dominated drainage basins. Journal of Geophysical
Research Earth Surface 114: doi: 10.1029/2008JF001088
ELEMENT S 373 OCT OBE R 2014
-
,&3 6DPSOH ,QWURGXFWLRQ 6ROXWLRQV IRU *HRFKHPLVWU\ � from
the leader in fluoropolymer manufacturing
Savillex Corporation “Geochemistry would has been proudly
not be where it is serving the today if it were not for
geochemistry Savillex Corporation.” community for over 35
years. –Dr.MikeCheatham, Our fluoropolymer Syracuse University
labware products are
used throughout the world for sample digestion, separations,
storage and many other applications. We understand the unique needs
of geochemists and now our new line up of ICP-OES and ICP-MS sample
introduction products combine the highest performance and the
lowest metal background with the ruggedness and reproducibility
required for routineanalysis.
All of our ICP sample introduction products are designed, molded
and tested in house, using only the
highestpuritygradePFAresins.
For technical notes, videos and to find your local Savillex
distributor, visit www.savillex.com.
Savillex Corporation Phone: 952.935.4100 | Fax: 952.936.2292
Email: [email protected] | www.savillex.com
Nebulizers – C-Flow
• C-Flow microconcentric PFA nebulizer range with the narrowest
uptake rate specification
• New C-Flow 35 with uptake rate of
35uL/min+/-7uL/min • C-Flow range for desolvators – standard
fitment on the CETAC Aridus II
• C-Flow 700d with removable uptake line for high solids
applica-tions – up to 25% TDS
• All C-Flows can be backflushed without tools
Inert Kits
• PFA kits with Scott type chamber • True double pass design
gives lower RSDs
• O-ring free end cap • Platinum or sapphire injectors •
Available for Agilent 7500/7700/8800 and Thermo Element
2/Neptune
1(:! 3XULOOH[é)(3DQG
3)$ %RWWOHV • Lowest metal background • Highest seal
integrity
http://www.savillex.com/mailto:[email protected]://www.savillex.com/
-
Climate Change Response Program National Park Service U.S.
Department of the Interior
Climate Change Direct Hire Authority Internship Opportunities in
the National Park Service
The implications of climate change are challenging and
far-reaching, particularly for land managers tasked with protecting
the resources of national parks and other protected areas. To meet
this challenge, managers need to encourage and make use of the
creative and innovative thinking of the next generation of youth
scientists and leaders.
The George Melendez Wright Initiative for Young Leaders in
Climate Change (YLCC) builds a pathway for exemplary students in
higher education to apply cutting-edge climate change knowledge to
park management. Through a summer-long internship, undergraduate
and graduate students will gain valuable work experience, explore
career options, and develop leadership skills under the mentorship
and guidance of the National Park Service. Parks and programs will
increase their capacity to understand and respond to climate change
and its impacts.
National parks and NPS programs develop and oversee structured
projects in one or more of the following interdisciplinary areas:
climate change science and monitoring; resource conservation and
adaptation; policy development; sustainable park operations;
facilities adaptation; and communication/interpretation/education.
During the internship, students apply critical thinking and problem
solving skills to climate change challenges and communicate with
diverse stakeholders. Interns who successfully complete the YLCC,
an approved Direct Hire Authority Internship program, will be
eligible to be hired non-competitively into subsequent federal jobs
once they complete their degree program. These jobs would be in the
Department of Interior (DOI), NPS, or one of the other bureaus
within the DOI. An intern must qualify for the job in order to be
hired non-competitively.
Quick Facts and Deadlines:
• The YLCC is managed cooperatively with the University of
Washington • Internship opportunities and application forms are
posted on
parksclimateinterns.org • Internships are 11-12 weeks (40
hours/week) during the summer • Interns are paid $14/hour plus
benefits • Applications are accepted from early December 2014 until
late
January 2015
Who was George Melendez Wright?
George Melendez Wright was deeply influential in bringing
science to the management of America’s national parks. Working as a
naturalist in Yosemite National Park in the 1920s, Wright argued
that good science was needed for effective conservation. In 1930,
he was appointed Chief of the Wildlife Division for the NPS where
he encouraged the agency to embrace science-based approaches to
conserving species, habitats, and other natural conditions in the
parks. Although he died while he was still a young man, Wright’s
legacy lives on in the NPS’s commitment to use the best available
science for preserving the resources of our National Parks.
For More Information: Tim Watkins, Climate Change Response
Program, NPS, [email protected]
mailto:[email protected]:parksclimateinterns.org
-
t: Michael R. Pence Governor \i !J Jerome M.Adams, MD,MPH. :
j,./ State Health Commissioner Indiana State
De12artment of Health An Equal Opporlunny Employer
October 29, 2014
To College and University Administrators:
The first cases of Ebola Virus Disease (EVD) diagnosed in the
United States have heightened awareness of our global community and
this serious disease. Italso raised the level of concern for the
safety of travelers both to the affected counh·ies, and those
returning to Indiana from an affected country, and the safety of
the academic community.
The Ebola virus is not spread through the air, by water or food,
or by casual contact. People with Ebola can only spread the Ebola
virus when they have symptoms. There is no lmown risk of
transmission if someone does not have symptoms. Ebola is only
spread through direct contact with blood or body fluids (including
but not limited to urine, saliva, feces, vomit and semen, or a
needlestick) of a person who is sick with Ebola or the body of a
person who has died from Ebola.
Currently in the U.S., individua ls at risk for developing EVD
are those who have arrived in the U.S. from Guinea, Liberia, or
Sierra Leone within the past 21 days (the maximum incubation period
for Ebola virus). Previous travel to these countries outside the
21-day incubation period is not a risk factor for Ebola.
Individuals who have had direct contact with identified Ebola
cases in the U.S. may also be at risk for the EVD if that contact
occurred at the time the case was symptomatic. Ebola symptoms
include fever, headache, nausea, vomiting, diaIThea, muscle or body
aches, and fatigue. The Indiana State Department of Health (ISDH)
website has more information about EVD at www.statehealth
.in.gov.
The Centers for Disease Control and Prevention (CDC) has
prepared a document specifically addressing the unique concerns of
colleges, universities , and students around the EVD occurring in
the West African countries of Guinea, Liberia, and Sierra Leone.
You can find that information at: http://wwwnc.cdc
.gov/travel/page/advice-for-college s-universities-and-student
s-about-ebola-in -west-africa.
The CDC has issued a Level 3 Warning travel advisory, urging all
U.S. residents to avoid non-essential travel to Liberia, Guinea,
and Sierra Leone because of unprecedented outbreaks of Ebola in
these countries. In addition, the CDC is screening all passengers
departing from airports in Liberia, Guinea, or Sierra Leone for
contacts with persons diagnosed with Ebola and symptoms of Ebola.
Exit screening involves travelers responding to a traveler health
questionnaire, being visually assessed for potential illness, and
having their body temperature measured before they board the
flight. Passengers with a positive screen are not permitted to
board flights.
To augment the screening process, the CDC Division of Global
Migration and Quarantine began screening passengers from Liberia,
Guinea, and Sierra Leone arriving at five U .S. ports of entry on
October 11, 2014. Beginning this weekend, all passengers traveling
from these countries will be routed through the five aiiports where
screening has been established. Passengers will complete a health
assessment form, provide destination and contact information, and
have their temperature checked. Anyone with risk factors for Ebola
will be further evaluated on site at the airport by a CDC medical
officer. Arriving passengers with symptoms will be
O 2NorthMeridian Street•lndlanapolls, IN46204 1 Topromote
andprovide 317.233.1325 tdd 317.233.5577 essential public health
services indiana 1 www.statehealth.ln.gov · AStatethat
http://wwwnc.cdc/http://www.statehealth.ln.gov/www.statehealth
-
transported to a designated hospital for medical evaluation in
the mTival city. Those with risk factors will be restricted from
traveling on commercial conveyances (air, bus, train,
taxi/limousine) until the 21-day incubation period has passed.
Travelers at low risk will be allowed to proceed to their
destinations, with notification provided to the state health
department. The ISDH has already begun receiving notification about
any traveler with Indiana as a destination and has an established
system, with local public health officials, for monitoring these
travelers for fever and other symptoms, so they can be immediately
hospitalized should they develop symptoms of Ebola. All passengers
arriving from the Liberia, Guinea, and Sierra Leone, regardless of
their exposure level, will be monitored by ISDH and local health
depmiments twice daily for 21 days. This includes, checking
temperature and symptoms.
To read more about enhanced screening of travelers from
Liberian, Guinea, and Sierra Leone at airpo1is in the
U.S.,pleasevisit the CDCwebsite
at:http://www.cdc.gov/media/releases/2014/p1008-ebola-screening.html.
CDC has strongly recommended that people avoid non-essential travel
to Guinea, Liberia, or SierraLeone at